Houghton Mifflin Harcourt just released a "new" book by J.R.R. Tolkien: Beren and Lúthien. The book is actually a compilation of Tolkien's earlier descriptions of the love story between Beren, a mortal man, and Lúthien, an immortal elf, which are apparently scattered throughout his writings. According to the publisher's description, Christopher Tolkien (the book's editor and Tolkien's son):

"...attempted to extract the story of Beren and Lúthien from the comprehensive work in which it was embedded; but that story was itself changing as it developed new associations within the larger history. To show something of the process whereby this legend of Middle-earth evolved over the years, he has told the story in his father's own words by giving, first, its original form, and then passages in prose and verse from later texts that illustrate the narrative as it changed. Presented together for the first time, they reveal aspects of the story, both in event and in narrative immediacy, that were afterwards lost.

I can't believe there's a burning demand for this, but you never know: the last book of semi-recycled content released by Tolkien's estate was at the top of the Times bestseller list for weeks.